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Signing TLS handshakes inside a TPM

bschaatsbergen.com

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Re: Signing TLS handshakes inside a TPM

#11

Post by madduci »

ram_rattle wrote: post #5

Nothing new here, attested TLS was being discussed in IETF for quiet sometime right? https://datatracker.ietf.org/doc/draft-fossati-tls-attestati... https://www.youtube.com/watch?v=MF9AwkMJOlw

Exactly, you could do this also with the Microsoft Cryptographic Provider long time ago, which is the basic Provider called by the go-tpm library, when running under Windows

Re: Signing TLS handshakes inside a TPM

#12

Post by zx8080 »

ranger_danger wrote: post #4

Let's hope this doesn't get picked up by the (corporate) masses... the last thing I want is my browser offering personal TLS certificates to every server I visit as some kind of identity verification or fingerprint/tracking. It's bad enough that ssh does this by default with all your keys.

This is most probably where it's going in less than a year. The recent campaign "Safer with Google" in Chrome hints to this.

Re: Signing TLS handshakes inside a TPM

#13

Post by bschaatsbergen »

duk3luk3 wrote: post #2

Sounds interesting; too bad all we get is text made up by an LLM rather than any of the author's insights.

Author here. All of it is mine, the library (https://github.com/bschaatsbergen/go-tpm-tls) and the benchmarks (https://github.com/bschaatsbergen/go-tpm-tls-bench) and the working notes. English isn't my first language, so I edit a lot, and I can see how that comes out flat. I've been over it once more; hopefully it reads better now. Thanks for saying so rather than just closing the tab.

Re: Signing TLS handshakes inside a TPM

#15

Post by ram_rattle »

bschaatsbergen wrote: post #10
ram_rattle wrote: post #5

Nothing new here, attested TLS was being discussed in IETF for quiet sometime right? https://datatracker.ietf.org/doc/draft-fossati-tls-attestati... https://www.youtube.com/watch?v=MF9AwkMJOlw

That's right, I'm learning in public here. That draft is a different direction though, they change the handshake: new TLS extensions carry the evidence, and the far end appraises the platform during the connection. What I'm doing changes nothing on the wire, the verifying side has no idea a TPM is involved. In RATS ( https://www.rfc-editor.org/rfc/rfc9334.html ) we prove a machine is sound by measuring it and apprais…

Never mind, I had no idea who you where, looked you up, please take a bow, apologies if the comment came out rude, more power to your work and agree learning in public and publishing more will what will make this idea better.

Hat Tip!

Re: Signing TLS handshakes inside a TPM

#16

Post by donavanm »

psanford wrote: post #14

I wish the author provided some latency numbers for this. One issue with tpms is that they are slow relative to performing the same operation on a modern CPU.

Thats the “what it costs” section? Im a bit impressed if they are down to ~3ms per handshake. When I last looked at TPM signing (many years ago) it was more like single digit transactions per second.

That said, even 3ms TPM signatures are going to be for special cases or novelty. Plain old CPU tls will do about 1ms cpu time per request which will scale by cpu core count. One or two orders of magnitude more throughput per host.

Re: Signing TLS handshakes inside a TPM

#17

Post by bschaatsbergen »

psanford wrote: post #14

I wish the author provided some latency numbers for this. One issue with tpms is that they are slow relative to performing the same operation on a modern CPU.

Author here. There's a benchmark table further down the post, the numbers come from this repo if you want to run them yourself: https://github.com/bschaatsbergen/go-tpm-tls-bench

Re: Signing TLS handshakes inside a TPM

#18

Post by KaiserPro »

For a company I work for I needed to ship a machine through unknown channels and have some confidence that it wasn't fiddled with.

my threat model was reasonably technical engineer swapping drives for some reason, or someone claiming that the machine is "different". (no nation state shit)

after the machine was imaged, it would connect to our central config server, get its hostname and exchange keys which would be embedded in the TPM.

once the machine is shipped and booted, it'll check in and sign a challenge. any kind of action on the central API could have a challenge. Each machine is attested at least once an hour.

I'm not sure how "secure" it all is, but it seems to work.

Re: Signing TLS handshakes inside a TPM

#19

Post by thomashabets2 »

Looks like speeds have picked up since I last looked at this, when a signature in TPM took 0.7s and no concurrent capacity.

https://blog.habets.se/2012/02/Benchmarking-TPM-backed-SSL.h...

https://blog.habets.se/2012/02/TPM-backed-SSL.html

Well, it's been over 14 years so I should hope so.

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